For safe operation all automobiles are provided with adjustable headlamps. Modern headlamp assemblies contain both high and low beam bulbs within a common housing which may be adjusted from the interior of the vehicle engine compartment. The aim of the headlamps must be periodically adjusted to ensure that the light from the vehicle headlamps is properly directed onto the vehicle path without being directed into the eyes of the driver of an oncoming vehicle.
In the interest of producing a low cost device having lubricious qualities, it is desirable to have a headlamp adjusting mechanism assembled from a few molded plastic parts. Such a mechanism is disclosed in Reiland U.S. Pat. No. 4,965,706, the disclosure of which is hereby incorporated by reference thereto. This mechanism utilizes a screw which may be rotated to elevate a vertical cam which engages with a slot in a horizontally movable cam to move the second cam and to cause the pivoting of a headlamp assembly connected thereto. Such a mechanical linkage has the advantageous property of requiring very little effort to adjust the headlamp, but being generally insensitive to movements of the headlamp which might cause the mechanism to come out of adjustment. However, for accurate adjustment it is important that the cam surfaces meet in tight engagement. Significant variations in the dimensions of the plastic parts would introduce sloppiness into the response of the mechanism or would cause the cams to lock against one another. Proper engagement is achieved by requiring strict tolerances in the production of the mechanism parts. As the manufacture of plastic parts becomes considerably more expensive if maintenance of close tolerances is required, a headlamp adjusting mechanism which operates effectively despite variations in the dimensions of its parts would be much more economically produced and would have advantageous performance properties.